Biotin and Leucine Alone or in Combination Promoted the Synthesis of Odd- and Branched-Chain Fatty Acids in the Rumen In Vitro

The odd- and branched-chain fatty acids (OBCFA) accumulated in ruminant products are a class of beneficial fatty acids for human health. Since biotin and leucine are involved in OBCFA synthesis, this study aimed to evaluate their effect on OBCFA synthesis in vitro. There were four treatments: the control group that only provided the basal diet, or the basal diet supplemented with biotin (4 mg/kg dry matter, DM), leucine (4 g/kg DM), or a combination of biotin (4 mg/kg DM) and leucine (4 g/kg DM). The results showed that biotin promoted the degradation of DM ( p < 0.10), while leucine significantly increased the concentration of branched-chain volatile fatty acids and valerate ( p < 0.05). The concentrations of total odd-chain fatty acids, total iso , total anteiso , total branched-chain fatty acids, total OBCFA, and total fatty acids were significantly increased by the supplementation of biotin or leucine ( p < 0.05). Biotin and leucine significantly stimulated the activities of acetyl-CoA carboxylase, fatty acid synthase, and malonyl-CoA, with a significant interaction effect ( p < 0.05). In conclusion, the results of this study suggested that biotin and leucine can be used as effective nutrition strategies to promote OBCFA synthesis.